Method of making carbamoyl sulfoxide derivatives

ABSTRACT

Intermediate compounds useful for manufacturing herbicidally active sulfoxide compounds are described herein. The compounds have the following generic formula:   wherein R and R1 are lower alkyl; and R2 can be selected from the group consisting of phenyl and benzyl.

United States Patent [191 Tilles 51 July 22,1975

[ METHOD OF MAKING CARBAMOYL SULFOXIDE DERIVATIVES [75] Inventor: Harry Tilles, El Cerrito, Calif.

[73] Assignee: Stauffer Chemical Company,

Westport, Conn.

22 Filed: June 13, 1973 21 Appl. No.: 369,676

Related U.S. Application Data [63] Continuation of Ser. No. 280,364, Aug. 14, 1972,

abandoned.

[52] U.S. Cl 260/551 R; 260/455 A; 260/607 A;

71/100; 71/98 [51] Int. Cl. C07C 103/32; CO7C 147/14 [58] Field of Search 260/551 Primary Examiner--Harry I. Moatz Attorney, Agent, or F irm--Daniel C. Block 57 ABSTRACT wherein R and R are lower alkyl; and R can be selected from the group consisting of phenyl and benzyl.

1 Claim, No Drawings METHOD OF MAKING CARBAMOYL SULFOXIDE DERIVATIVES This is a continuation, of application 4 Ser. No. 280,364, filed Aug. 14, 1972, now abandoned. 1

DESCRIPTION OFTHE INVENTION 0 1 This invention is directed to a novel group of compounds which may be generally described as sulfoxide derivatives of thiocarbamates which are highly active herbicides. These compounds are represented by the generic formula: 1 v

wherein R, R and R have been defined above. The reaction is carried out in the presence of a solvent such as chloroform, methylene chloride, benzene and toluene, and at a reduced temperature of from about -C. to about 25C. The amount of oxidizing agent used must be at least one molar equivalent to form the sulfoxide derivative. The reaction is complete when no oxidizing agent remains.

The thiocarbamate compounds are known herbicides and their method of synthesis is known; see US. Pat. Nos. 2,913,327, 2,983,747, 3,133,947, 3,175,897 and 3,185,720 for example. However, the use of these thiocarbamates as reactive intermediates to form other compounds that also have pesticidal activity is unexpected.

In order to illustrate the merits of the present invention the following examples are provided:

EXAMPLE 1 A solution was formed containing 10.5 g. (0.05 mole) of S-ethyl N-ethylphenylthiocarbamate in 200 cc. of methylene chloride in a reaction vessel. This solution was cooled to -l5.5C., wherein 10.7 g. (0.0525 mole) of m-chloroperoxybenzoic acid was added over a period of six minutes. The reaction mass was maintained at this temperature for an additional 1 hour, wherein the temperature was allowed to go to 55C. for another V2 hour. Thereafter, the reaction mass was allowed to obtain a temperature of 19.5C., wherein the cold mixture was filtered and the cake was washed with two portions of 25 cc. of methylene chloride. The combined filtrate was washed with four portions of 100 cc. of 5% sodium carbonate solution and two portions of cc. of,water, dried over magnesium sulfate and concentrated. in a rotary evaporator, firstunder water pump vacuum and finally under high vacuum, to yield 9.8 g. of product, n 1.560.-

Other compounds were prepared in an analogous manner starting with the appropriate starting materials as outlined above. The following is a table of compounds representative of those embodied by the present invention. Compound numbers have been assigned to them and are used for identification throughout the balance of the specification.

HERBICIDAL SCREENING TESTS As previously mentioned, the novel compounds herein described are phytotoxic compounds which are useful and valuable in controlling various plants species. Compounds of this invention are tested as herbicides in the following manner.

PRE-EMERGENCE HERBlClDE SCREENING TEST Using an analytical balance, 20mg. of the compound to be tested is weighed out on a piece of 'glassine weighing paper. The paper and compound are placed in a 30 ml. wide-mouth bottle and 3, ml. of acetone containing 1 percent Tween 20 is added to dissolve the compound. If the material is not soluble in acetone, another solvent such as water, alcohol or dimethylformamide (DMF) is used instead. When DMF is used, only 0.5 ml. or less is used to dissolve the compound and then another solvent is used to make the volume up to 3 ml. The 3 ml. of solution is sprayed uniformly on the soil contained in a small Styrofoam'flat one day after planting weed seeds in the flat of soil. A No. 152 DeVilbiss atomizer is used to apply the spray using compressed air at a pressure of 5 lb./sq. in. The rate of application is 8 lb./acre and the spray volume is 143 gal/acre.

On the day preceding treatment, the Styrofoam flat, which is 7 inches long, 5 inches wide and 2.75 inches deep, is filled to a depth of 2 inches with loamy sand soil. Seeds of seven different weed species are planted in individual rows using one species per row across the width of the flat. The seeds are covered with soil so that they are planted at a depth of 0.5 inch. The seeds used are hairy crabgrass (Digilaria sanguinalis), yellow foxtail (Setaria glauca), watergrass (Echinochloa crusgalli), red oat (Avena sativa), redroot pigweed (Amaramhus retroflexus), Indian mustard (Brassica juncea) and curly dock (Rumex crispus). Ample seeds are planted to give about 20 to 50 seedlings per row after emergence depending on the size of the plants.

After treatment, the flats are placed in the greenhouse at a temperature of 70 to 85F. and watered by sprinkling. Two weeks after treatment the degree of injury or control is determined by comparison with untreated check plants of the same age. The injury rating from to 100 percent is recorded for each species as percent control with 0 percent representing no injury and 100 percent representing complete kill.

POST-EMERGENCE I-IERBICIDE SCREENING TEST Seeds of six plant species, including hairy crabgrass, watergrass, red oat, mustard, curly dock and Pinto beans (Phaseolus vulgaris) are planted in the Styrofoam flats as described above for pre-emergence screening. The flats are placed in the greenhouse at 70 to 85F. and watered daily with a sprinkler. About to 14 days after planting when the primary leaves of the bean plants are almost fully expanded and the first trifoliate leaves are just starting to form, the plants are sprayed.

The spray is prepared by weighing out mg. of the- TABLE II HERBICIDAL ACTIVITY SCREENING RESULTS Compound Per Cent Control at 8 lb./A

Number Pre-emergence Post-emergence Average for seven plant species 'in the pre-emergence test and for six plant species in the post-emergence test.

What is claimed is: 1. A process of manufacturing a herbicidally active compound having the formula:

00 II II wherein R and R is lower alkyl and R is selected from phenyl and benzyl; comprising the steps of:

a. reacting an oxidizing agent selected from mchloroperoxy benzoic acid with a thiocarbamate in the presence of a solvent, said thiocarbamate having the formula:

wherein R, R, and R have been previously defined;

b. said reaction being carried out at a temperature of between 25C and 25C; c. said oxidizing agent being present in an amount of at least one molar equivalent. 

1. A PROCESS OF MANUFACTURING A HERBICIDALLY ACTIVE COMPOUND HAVING THE FORMULA: 